Replace GTS with CDT (#617)

This removes the dependency on GTS.

It removes the Mesh boolean operations functions, which were part of the building editor in Gazebo-classic but are unused in modern gazebo.
It replaces the GTS delaunay triangulation with the header-only CDT library.

---------

Signed-off-by: Michael Carroll <[email protected]>
Signed-off-by: Ian Chen <[email protected]>
Signed-off-by: Steve Peters <[email protected]>
Co-authored-by: Ian Chen <[email protected]>
Co-authored-by: Steve Peters <[email protected]>

.github/ci/packages.apt

@@ -5,7 +5,6 @@ libavformat-dev
 libavutil-dev
 libfreeimage-dev
 libgdal-dev
-libgts-dev
 libgz-cmake4-dev
 libgz-math8-dev
 libgz-utils3-dev

CMakeLists.txt

@@ -68,13 +68,6 @@ gz_find_package(FreeImage VERSION 3.9
   REQUIRED_BY graphics
   PRIVATE_FOR graphics)
 
-#------------------------------------
-# Find GNU Triangulation Surface Library
-gz_find_package(
-  GTS PRETTY gts PURPOSE "GNU Triangulation Surface library"
-  REQUIRED_BY graphics
-  PRIVATE_FOR graphics)
-
 #------------------------------------
 # Find GDAL
 gz_find_package(GDAL VERSION 3.0

Migration.md

@@ -5,6 +5,22 @@ Deprecated code produces compile-time warnings. These warning serve as
 notification to users that their code should be upgraded. The next major
 release will remove the deprecated code.
 
+## Gazebo Common 5.X to 6.X
+
+### Modifications
+
+1. Removed the `graphics` component's dependency on the GTS
+   (GNU Triangulated Surface) library which was used for doing triangulation
+   and CSG Boolean operation by the `MeshManager`. The Delaunay triangulation
+   function now uses the CDT (Constrained Delaunay Triangulation) library.
+
+### Deletions
+
+1. **MeshManager.hh**
+    + `void CreateBoolean(const std::string &_name, const Mesh *_m1,
+          const Mesh *_m2, const int _operation,
+          const gz::math::Pose3d &_offset = gz::math::Pose3d::Zero)`
+
 ## Gazebo Common 4.X to 5.X
 
 ### Deprecations

codecov.yml

@@ -1,3 +1,7 @@
 ignore:
+  - "graphics/src/tiny_obj_loader.h"
+  - "graphics/src/CDT"
+  - "graphics/src/VHACD"
   - "profiler/src/Remotery/lib"
   - "profiler/src/Remotery/vis"
+  - "src/win_dirent.h"

coverage.ignore.in

@@ -1,4 +1,5 @@
-profiler/src/Remotery/*
 graphics/src/tiny_obj_loader.h
+graphics/src/CDT/*
+graphics/src/VHACD/*
+profiler/src/Remotery/*
 src/win_dirent.h
-graphics/src/tinyxml2/*

graphics/include/gz/common/DelaunayTriangulation.hh

@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) 2024 Open Source Robotics Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#ifndef GZ_COMMON_DELAUNAYTRIANGULATION_HH_
+#define GZ_COMMON_DELAUNAYTRIANGULATION_HH_
+
+#include <vector>
+
+#include <gz/math/Vector2.hh>
+
+#include <gz/common/graphics/Export.hh>
+
+
+namespace gz::common
+{
+class SubMesh;
+
+/// \brief Perform delaunay triangulation on input vertices.
+/// \param[in] _vertices A list of all vertices
+/// \param[in] _edges A list of edges. Each edge is made of 2 vertex
+/// indices from _vertices
+/// \param[out] _submesh A submesh that will be populated with the
+/// resulting triangles.
+/// \return True on success.
+bool GZ_COMMON_GRAPHICS_VISIBLE DelaunayTriangulation(
+                  const std::vector<gz::math::Vector2d> &_vertices,
+                  const std::vector<gz::math::Vector2i> &_edges,
+                  gz::common::SubMesh *_submesh);
+
+}  // namespace gz::common
+#endif  // GZ_COMMON_DELAUNAYTRIANGULATION_HH_

graphics/include/gz/common/MeshManager.hh

@@ -270,16 +270,6 @@ namespace gz
       /// \param[in] _scale scaling factor for the camera
       public: void CreateCamera(const std::string &_name, const float _scale);
 
-      /// \brief Create a boolean mesh from two meshes
-      /// \param[in] _name the name of the new mesh
-      /// \param[in] _m1 the parent mesh in the boolean operation
-      /// \param[in] _m2 the child mesh in the boolean operation
-      /// \param[in] _operation the boolean operation applied to the two meshes
-      /// \param[in] _offset _m2's pose offset from _m1
-      public: void CreateBoolean(const std::string &_name, const Mesh *_m1,
-          const Mesh *_m2, const int _operation,
-          const gz::math::Pose3d &_offset = gz::math::Pose3d::Zero);
-
       /// \brief Perform convex decomposition on a submesh.
       /// The submesh is decomposed into multiple convex submeshes. The output
       /// submeshes contain vertices and indices but texture coordinates